Electron-discharge device



Oct. 29, 1929. J JOHNSON 1,733,603

ELECTRON DISCHARGE DEVICE Filed July 2, 1925 lm emor: Ja/m .5. Job/20mPatented Oct. 29, 1929 uni-Tan snares JOHNiB. JOHNSON,',OF ELMHURST,"NEVJ YORK, ASSIGNOR' TOWESTERN ELECTRIO COMQ PANY, INCORPORATED, 0F-NEWYORK, N. Y., A CORPORATION OF NEW- YORK? I 'nnncrnon-nrsormnen DEVICEApplication filed July 2,

This invention'rel'ates to electron discharge devices an'd circuitsemploying the same, and particularly electron discharge devicesemploying thermionic cathodes and circuit arrangements for heating thecathodes with fluctuating current.

One ofthe'olijectsgof the invention is'to improve the action'oit anelectron discharge devise;

A furtlierohject of the invention is to prevent" disturhancesfinftheoutput of an electrondiscliarge device due to'vari'ations in the cathodeheating current. i

It is often desirable toheat' thecathode of electron discharge devicesbymeans'oitv current from an a'lternating or varying-sourceofipotential. \Vhen this is: done, however, the potential het'weentliecathode and control electrode and between the cathode and anode variesin accordance With the voltage impressed on theYcat'hode, thus producingfluctuations A in a the output current, ofthe devicei I In accordancewith this invention; the oath- OdE control electrode. and' anodie'arearranged in parallel relationship Within an enclosing vessel and tapsBrought out from both ends oi each. electrode, so that a voltage equalto that impressed on the" cathode for heating maybe impressed on boththe control electrode and the anode. Adjacent pointsonjthe threeelectrodes are thereby maintained at the same potential irrespective ofvariations in the cathode heating current and no changes Willhe'produced in thespa'cecurrent thereby. I VlZhen the cathode oit' 'anelectroirdischarge device is heated by means of an electric currentflowing therethrough the two terminals of the' cathode Will be atdifferent potentials duertotheRI drop; i Vhen theordinarytype of anodeis employed and this anode main.- tainedat a definitepotential Withrespect to the cathodeby' means of" anexternal source, the; anodecathodepotential will vary at differentp'oints' along the'cathode; As is Wellrecognizediirthe art the output of an electron discharge device isWithin certain limits dependent noon the anode-cathode potential.Therefore, if the external source is adiustod to such a value as to givemaximum efficiency 1925. Serial. No. 41,051.

PATENT oFFrc-Ej l of oneration other points on thecathode' will i beoperating'at ineiiicient potentials'and the entire area of the'catliodeWill not be used to the greatest advantage; Theideleterious results of.this effect Willhe most pronounced in devices provided With cathodes of?considre erahle length Where a large cathode area is desirable forgiving, a, high energyioutput'.

The arrangement" of this invention. above described Which the threeelectrodes-Tare arranged parallel and the same long tudinal potentialimpressed" thereon. to maintain ad jacent pointsat the same potential?makes'it possible to maintain allpoints onithe cathode A three-electrodevacuumtubeg 3;- having-a I filamentary cathode 4, agcontrol electrode orgrid 5 and ananode6 arrangedfa'ccording to this lIlVentlOIllS showninan"ainp hhercircu t equipped with means for heating the, 'cath-l ode withalternating current, the electrodes are merely shown diagrammatically asany particular form" is notmaterial to the inv'ention. The grid andanode are arranged parallei toone another and to-thecathodeand each is,provided with terminals at both ends. WVhile it is preferahl'e to makethe electrodes of parallel wiresarranged non-inductively so as not tointroduce any magnetic "fields which \vould'afiect the electron stream,the grid and anodemay readily be con structed of parallel plane,cylindrical? or other suitable shape.

The grid and anode must be of comparatively high resistance so as not tobe heated when a voltage equah to thecath'ode voltage isimpressecha'long them, While the cathode is made in the usual manner sothat it is heatedto incandescence to give *oifflelectrons.

Filament heating current-is supplied from 9 an alternating currentsource 'Z; through a transformer-8 which is provided with a p'ri' maryWinding 9 connected to the source Tthrough a rheostat 10. A secondaryWinding 11 of tlietran'sformer is c'onneote'dlto'the cathode 4 forsupplying current thereto. Two other secondary windings 12 and 18 arealso provided for applying equal voltages across the grid 5 and theanode 6. These windings each have the same number of turns and'are woundin the same direction as the winding 11, so that equal voltages of thesame phase are impressed on the electrodes to maintain adjacent pointson all three at the same potential. By connecting the rheostat in theprimary circuit the filament current can be controlled without affectingthe equality of the electrode voltages.

The tube is associated with the other apparatus in the amplifier circuitin the usual manner, the connections to the electrodes preferably beingmade at the electrical centers of their respective transformer windingsso as to keep the inductive coupling'between the input and outputcircuits at a minimum. Thus the secondary winding of the inputtransformer 14 is connected in series with the grid biasing battery 15to the mid-points of the grid winding 12 and the cathode winding 11while the receiver 16, representing the output circuit, is connected inseries with the plate battery 17 to the mid-points of the anodewinding13 and the cathode winding 11. If it is desired, the mid-point of thecathode winding may be grounded by means of a connection 18. r

The invention has been described with respect to an audio frequencyamplifier circuit but may obviously be applied to other circuits such asdetectors, high frequency amplifiers oreven oscillators if desired.

- -What is claimed is:

1. An electron discharge device comprising a thermionic cathode, acontrol element and an anode arranged in parallel space relationship,means for supplying alternating heating current to said cathode, andmeans 7 ing current thereto, andmeans for impressing an equalfluctuating potential from the same source on said control electrode toprevent fluctuations in said heating current from producingdisturbancesin the space current of said device.

4. An electron c ischarge device comprising a thermionic cathode, acontrol electrode, and

an anode arranged in parallel space relation- 7 I cathode heatingcurrent.

ship, means for supplying fluctuating cur-' rent for heating saidcathode, and means for impressing current from the same source on saidcontrol electrode and anode to always maintain adjacent points on saidthree electrodes at the same potential with regard to the cathodeheating current.

5. An electron discharge device comprising an enclosing vesselcontaining a thermionic cathode, a control electrode, and an anodearranged in parallel space relationship, means for impressingalternating current on said cathode for heating the same and means forimpressing alternating current of the same potential and phase on saidcontrol electrode and anode to maintain adjacent points on said threeelectrodes at the same potential.

6. In combination, an electron discharge device having a thermioniccathode, a control electrode and an anode arranged in parallel spacerelationship and eachprovided with terminals at both ends, a source ofalternating current and a transformer having a primary winding connectedto said source, a secondary winding connected to the terminals of saidcathode for. supplying heating current and two other secondary windingshaving the same number of turns as said first secondary windingconnected to said control electrode and anode, respectively, forimpressing thereon a potential of the same phase and equal to thepotential impressed on the cathode to maintain adjacent points onsaidthree electrodes at the same potential with regard to the 7 Anelectron discharge device comprism a filamentary cathode, a controlelectrode,

an anode, said control electrode and anode being arranged parallel toone another and to said cathode and being of comparatively highresistance so as not to be heated to incandescence when a voltage equalto the oathode voltage is impressed thereon, means for supplying analternating current to said cathode for heating and means for impressingan alternating current of the same phase and voltage on said controlelectrode and anode to maintain adjacent points on said three electrodesat the same potential.

8. An electron discharge device comprising a thermionic cathode, acontrol electrode, an anode, a source of alternating current, and meansfor heating the cathode by said alternating current and for impressingalternatingcurrent from said source in the same phase

